Wading vehicle depth measurement apparatus

ABSTRACT

A vehicle ( 100 ) comprises a water depth sensing apparatus ( 114 ) comprising a capacitive resistive sensor.

TECHNICAL FIELD

The present invention is concerned with an apparatus for measuring the water level relative to a vehicle body. More particularly, but not exclusively, the present invention is concerned with the measurement of the water level of a wading vehicle and providing such information to a driver of the vehicle. Aspects of the invention relate to a wading vehicle depth measurement apparatus, to a vehicle, a vehicle body component and to a method.

BACKGROUND

An off-road vehicle may be defined as a road vehicle having some off-road capability designed therein, such as four wheel drive. Off road vehicles are often required to travel through water to reach their intended destination. Travel through deep water (over about 0.3 m in depth) is known as “wading”. Known off-road vehicles are designed to wade, and comprise suitably sealed closures to avoid ingress of water into the passenger compartment. The engine air intake is positioned at an elevated position (normally directly in front of and below the windscreen) to prevent water being ingested into the engine, and this intake will often dictate the maximum level of water relative to the body that the vehicle can wade through without risking water ingestion and engine damage.

Prior art methods of determining if the water level is safe to wade through include referring to depth gauges, e.g. permanent graduated poles situated within the water in the case of fords and measurement of the depth by the driver using a partially submerged stick or pole.

The former method requires such a gauge to be present, and the latter method involves the driver exiting the vehicle. The latter method in particular will often not reveal the deepest point unless the driver wades in, which is undesirable and dangerous.

Both methods only reveal the absolute depth of the water (from the ground to the water surface). This is often not sufficient to make an accurate assessment of the vehicle's capability to pass. The knowledge that the driver requires is, instead, what the water level is relative to a point on the vehicle body (e.g. the air intake). The distance between the bottom of the vehicle tyres and the air intake is variable (due to suspension travel, tyre pressure variations etc) and as such with known methods the driver must take account of a potential margin of error in making his decision. This is undesirable as the driver may decide not to proceed through water which the vehicle is, in fact, capable of wading through.

An aim of the present invention is to at least mitigate the above mentioned problems.

SUMMARY

Aspects of the invention relate to a wading vehicle water level measurement apparatus, a vehicle, a vehicle body component and a method as claimed in the appended claims.

According to another aspect of the invention for which protection is sought, there is provided a wading vehicle water level measurement apparatus comprising a capacitive or resistive water level sensor exposed in use to water at wading depth.

By exposed, we mean for example that the apparatus is attached to, or forms part of a surface which is not only contactable by the environment in which the vehicle is immersed, but is immersed to a level representative of the level of liquid external to the vehicle. In other words, when the vehicle is wading, the level of liquid about the sensor must be the same as the level of liquid external to the vehicle. For example, external surfaces of components in the engine bay are usually exposed to water at wading depth. Optionally, the sensor is positioned on a body component; i.e. a component which is substantially fixed in position relative to the engine air intake.

In one embodiment, the sensor is configured to detect water level over a prescribed range. Optionally, the sensor is configured to detect the water level either continuously or in a plurality of discrete levels. In one embodiment five such levels are provided.

Resistive or capacitive sensors rely on the electrical properties of a substance disposed between two electrodes. The resistance of water is lower than that of air (for a resistive sensor), and the dielectric constant of water is many times higher than air (for a capacitive sensor).

To provide a continuous measurement, the sensor may comprise a pair of elongate electrodes oriented in a vertical sense (with respect to the vehicle local coordinate system) and the water level may be determined by measuring the resistance/capacitance across the sensor electrodes. The change in water level will be generally proportional to the change in resistance or capacitance.

Alternatively, the sensor may provide a discrete, piecewise, measurement. In other words the sensor may comprise an array of electrode pairs oriented in the vertical sense, and the water level determined by a change in resistance/capacitance at the highest electrode pair. The sensor may comprise a single electrode on one side of the sensor and a plurality of electrodes on the opposing side, with the resistance or capacitance being sequentially measured between each of the plurality and the single opposing electrode. One electrode may be a component of the vehicle, such as a body panel or frame component.

Optionally, the sensor is positioned below the lowest water-critical component. For example, the sensor may be positioned below the engine air intake.

The sensor may be self-activating, or may be activated by a wading sensor which detects the presence of water at a low level with respect to the vehicle. The wading sensor may be an ultrasonic sensor, such as PDC (parking distance control) sensor, configured to detect the presence of water upon immersion thereof.

According to another aspect of the invention there is provided a vehicle comprising wading vehicle water level measurement apparatus comprising a capacitive or resistive water level sensor exposed in use to water at wading depth.

The vehicle may include an attitude sensor or angular orientation sensor, such as an accelerometer or gyroscope, and a water level detection system comprising a memory and a processor, in which the memory is configured to store a water level measurement from the water level sensor and a vehicle orientation from the attitude sensor, the memory further storing software executable by the processor to determine a water level on the vehicle at a position spaced from the water level sensor.

Advantageously, the sensor can therefore be placed at a position spaced apart from e.g. the air intake should packaging and/or functional requirements dictate.

The sensors may be positioned on the front subframe, radiator support pack, bumper beam, wheel arch liner, suspension knuckle, lower arms or similar components.

Multiple sensors may be positioned across more than one component to measure water level at different heights in the vehicle body local coordinate system.

Alternatively, the sensor may be provided on a dedicated component such as an elongate member extending substantially vertically in the car body.

According to a further aspect of the invention for which protection is sought there is provided a vehicle having a wading vehicle water level measurement apparatus comprising a plurality of vehicle mounted capacitive or resistive water level sensors positioned at different transverse and/or longitudinal positions in the vehicle body local coordinate system.

Optionally, the sensors are configured to detect a plurality of water levels. By comparing the water level at different positions on the body the angular position of the body whilst wading can be determined without recourse to an attitude sensor.

According to still a further aspect of the invention there is provided a method of detecting the wading depth of a vehicle and comprising the steps of providing on the vehicle a capacitive or resistive water level sensor, and determining wading depth according to the capacitance or resistance thereof, respectively.

Optionally, the method comprises the step of providing a vertical array of said sensors, each sensor being independent so as to indicate a discrete wading depth.

Optionally, the method comprises the step of interrogating each sensor in the array individually. In some embodiments the each sensor in the array is interrogated individually in a predefined sequence.

Optionally, the method comprises the step of interrogating each sensor in the array simultaneously.

The method may include the step of providing a plurality of said sensors around a vehicle, and interpolating the outputs thereof to indicate vehicle inclination.

Optionally, the method includes the steps of determining orientation of the vehicle from an orientation sensor, and determining a water level on the vehicle at a position spaced from said water level sensor.

Optionally, the method comprises the step of determining the highest electrode pair in the array which has experienced a change in resistance or capacitance.

According to yet a further aspect of the present invention for which protection is sought there is provided a vehicle body component comprising the wading vehicle water lever measurement apparatus described herein above.

Other aspects of the invention will be apparent from the appended claims, which include methods of determining wading depth and water level with respect to the vehicle.

Within the scope of this application it is envisaged that the various aspects, embodiments, examples, features and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings may be taken independently or in any combination thereof. For example, features described in connection with one embodiment are applicable to all embodiments unless there is incompatibility of features.

BRIEF DESCRIPTION OF DRAWINGS

Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying Figures, in which:

FIG. 1 is a schematic side view of a wading off-road vehicle comprising an apparatus according to embodiments of the present invention;

FIG. 2 is a detail view of a part of the vehicle of FIG. 1;

FIG. 3 is a schematic view of a sensor apparatus in accordance with an embodiment of the present invention;

FIG. 4 is a schematic view of a sensor apparatus according to another embodiment of the present invention;

FIG. 5 is a schematic view of a sensor according to still another embodiment of the present invention;

FIG. 6 is a schematic side view of a wading off-road vehicle comprising a second apparatus according to embodiments of the present invention;

FIG. 7 is a schematic side view of a wading off-road vehicle comprising a third apparatus according to embodiments of the present invention; and

FIG. 8 is a schematic side view of a wading off-road vehicle comprising a fourth apparatus according to embodiments of the present invention.

DETAILED DESCRIPTION

Referring to FIG. 1, a vehicle 100 comprises a body 102, a left front wheel 104 and a left rear wheel 106. The wheels 104, 106 (and their counterparts on the right hand side of the vehicle) are connected to the body 102 via a suspension (not shown). Each of the wheels 104, 106 comprises a tyre.

The wheels 104, 106 can move relative to the body 102 to define a ride height R between the lowermost point of the tyres (where they contact the ground) and the lowermost point on the body 102. The ride height R varies with suspension travel and may be varied by the driver (for example to move from an on-road mode when R is small to an off-road mode when R is large).

The body 102 comprises a windscreen 108 and a bonnet (or hood) 110 covering an engine bay. On the body 102 between the windscreen 108 and the bonnet 110 there is defined an engine intake orifice 112. The orifice 112 is connected to an air filter and intake manifold of the engine (not shown). The intake orifice 112 is positioned at a height H from the lowermost part of the body 102.

The vehicle 100 is shown wading through water 12 at a water depth D from a ground level 10. The water depth D should be distinguished from the water level represented by L which is the level of the water 12 above the lowermost point on the body 102.

It will be noted that although D can be measured (by a roadside gauge or a measuring stick), the distance L is unknown (as R can vary). In order to know whether the vehicle 100 can be taken through the water 12, the distance between the intake orifice 112 of the water level 10 needs to be determined.

Referring to FIG. 2, the front section of the vehicle 100 is shown. A level sensing apparatus 114 according to an embodiment of the present invention is shown in hidden line and is positioned within the engine bay on the engine bay bulkhead. If convenient an apparatus 114 could be positioned close to the front (and/or optionally at the rear) of the vehicle 100.

In other embodiments of the invention the sensor 114 may be positioned on one or more of the following components, but not limited to, front subframe, radiator support pack, bumper beam, wheel arch liner, suspension knuckle, lower arms or other similar component. Advantageously, such components are less prone to interference or erroneous water level measurement since they are at least partially shielded from splashing and/or precipitation. Sensors placed on these locations may provide more reliable measurements of the depth of the water being waded through.

Turning to FIG. 3, the level sensing apparatus 114 is shown in schematic detail. The apparatus 114 comprises a resistive sensor 116 having a first conductive plate 118 and a second conductive plate 120 spaced therefrom. The plates 118, 120 are parallel and offset to define a gap 122 therebetween. Each plate 118, 120 is connected to an electrical circuit 124 which is configured to measure the resistance of the sensor 116 (for example by either applying a voltage across the plates and measuring the current in the circuit or applying a constant current and then measuring the voltage across the plates. In some embodiments both voltage and current may be measured. In yet other embodiments the resistance or capacitance may be measured by coupling the sensor to a signal generator such as an oscillator, for example a sine wave oscillator, and measuring a change in the frequency or wavelength of the signal).

The plates 118, 120 are elongate and as the vehicle 100 wades, are at least partially submersed in water 12. Because the conductivity of water 12 is higher than that of air, the resistance of the sensor 116 will drop with increasing water level. There will be a linear relationship between length of the sensor electrodes immersed in water and the resistance of the sensor 116. If the sensor 116 is installed in a vertical plane then the water level L will be directly proportional to the resistance of the sensor. As such, once the sensor 116 is calibrated, the level L can be detected and the information provided to the vehicle systems and the driver. If the sensor 116 is installed on a non planar surface and/or the surface deviates from the vertical a different relationship will exist between the water level L and the resistance of the sensor 116, this will require a different calibration. For example the sensor 116 may be mounted on an arcuate surface of the wheel arch liner; a change in the water level L towards the lowermost end of the sensor 116 may result in a smaller change in the resistance of the sensor 116 than the same change in water level L towards the upper end of the sensor 116; since more of the sensor 116 may be immersed in water 12 as a result of the change in water level L in an upper region of the sensor than would be immersed in water 12 as a result of the same change in the water level L in a lower region of the sensor 116.

Turning to FIG. 4, there is illustrated an alternative sensor 216 according to another embodiment of the invention in which the sensor 216 comprises a series of electrode plate pairs each comprising a first electrode 218 and a second electrode 220. The pairs of plates are spaced in the vehicle height direction. One of the plates of each pair could comprise a vehicle body panel from which the other plate is separated by a dielectric material. Other electrically conductive components of the vehicle 100 could be used as one plate of the electrode pair.

In one embodiment, the resistance of the electrode pairs are simultaneously measured. It will be noted that the electrode pairs which are fully submerged will have a significantly lower resistance than the pairs that are not. Therefore the water level L can be measured by determining which is the highest of the electrode pairs with low resistance, since the height of each of electrode pairs with respect to the vehicle body 102 is known and the ride height R of the vehicle 100 is known the water level L can be calculated.

It will be noted that one of the electrode pairs may be partially submerged, and interpolation of resistance against the height of that electrode pair may be used to make the level measurement more accurate.

In an alternative embodiment, only one electrode pair at a time is measured, for example using a multiplexer. This will simplify the necessary circuitry. Each of the electrode pairs are measured sequentially, for example from the uppermost pair down to the the lowermost pair or from the lowermost pair up to the uppermost pair. In alternative embodiments other sequences are envisaged.

An advantage of the embodiment of FIG. 4 is that because the system relies on discretely positioned electrode pairs, changes in the properties of the water will not significantly affect the level measured.

Turning to FIG. 5, there is illustrated a sensor 316 according to a further embodiment. The sensor 316 comprises a first electrode plate 318 and a series of second electrode plates 320.

The sensor 316 works in a similar manner to the sensor 216, except that only the plates 320 need to be measured alternately (e.g. multiplexed).

It will be noted that all of the above embodiments may be used in a capacitive sense- that is the capacitance of the pairs of plates may be measured instead of the resistance on the assumption that the dielectric constant of water and air are different (as are their conductivity).

FIG. 6, illustrates yet another embodiment of the invention in which the vehicle 100 is shown having a measurement apparatus 114 as well as an ultrasonic sensor 126 mounted on the front of the vehicle 100. The sensor 126 could be a PDC (parking distance control) sensor.

The sensor 126 can be used to detect the presence of water 12 (the water 12 will affect the performance of the sensor) and this can trigger activation of the apparatus 114. Therefore the apparatus 114 can be dormant for most of the time except for when the vehicle 100 is wading. Alternatively, the apparatus 114 may be in a ready state, for example when the vehicle ignition switch is ‘on’ and be self activating.

Referring to FIG. 7, there is shown an alternative embodiment of the present invention in which a vehicle 400 has an apparatus 414 similar to the apparatus 114 but positioned at a horizontal distance A (in the car body local coordinate system) from the air intake 412 towards the front of the vehicle 400. The apparatus 414 may be positioned away from the intake for ease of installation (for example packaging, access or wiring location).

The vehicle 400 is illustrated backing down a slope 6 (for example a slipway). The angle of the slope 6 shown in FIG. 7 is exaggerated for clarity.

The vehicle 400 further comprises an angular orientation sensor 450 which detects the tilt angle B of the vehicle 400. As can be observed in FIG. 7, because the vehicle 400 is tilted, the water level L at the intake 412 is high, whereas the level L′ measured by the sensing apparatus 414 would be lower. Therefore there is a risk that the driver may travel into unsuitable depths of water 12.

In order to compensate, the vehicle 400 comprises a memory and processor (not shown) configured to adjust the reading L′ to compensate for the angle B. In this instance, since the horizontal distance A is known the level L can be calculated by:

L=L′+A·tan (B)

The apparatus 414 may comprise sensor electrodes moulded into the wheel arch trim or similar.

In a further alternative embodiment of the present invention, shown in FIG. 8, a vehicle 500 is shown driving down an inclined slope 2 whilst wading through water 4. The vehicle 500 comprises a water level sensor 502 (similar to those described above, or alternatively the sensor could be a hydrostatic pressure sensor or any other sensor capable of measuring water depth) and a vehicle angular orientation sensor 504.

The water level sensor 502 measures a water level L which is combined with an on-board ride height measurement to provide a water depth D1 at the sensor 502. The angular orientation sensor 504 measures an inclination angle C of the vehicle 500.

The vehicle 500 comprises a processor and memory (not shown); the memory having software loaded thereon which is executable by the processor to estimate a depth D2 at a distance X from the front of the vehicle.

The depth D2 is calculated by the relation:

D2=D1+Y·tan C

where Y is the sum of the distance X and the distance from the front of the vehicle to the sensor 502.

The system allows the user to select values of X, and may display values of D2 for multiple values of X. FIG. 8 shows the system estimating depth in the direction of travel, but the system can also estimate depth in other directions (e.g. left and right) by using the roll angle of the vehicle 500 as well as the pitch angle.

Variations are possible within the scope of the present invention.

One or both of the electrodes may be a vehicle component. For example, the system may be configured to measure the resistance or the capacitance between two conductive but electrically isolated parts of the vehicle body, such as panels.

The apparatus may be provided as a retrofit system on a replacement vehicle component. The present application claims priority to UK patent application numbers filed by the present applicant on 15 Dec. 2010 having the application numbers GB1021268.6, GB1021278.5, GB1021272.8, GB1021297.5, GB1021295.9 and GB1027296.7, the contents of each of which are expressly incorporated by reference in their entirety.

The present application is related to the PCT applications, and to UK Patent Applications, filed concurrently with the present application, by the applicant of the present application, which are listed below:

-   -   1. PCT application ______ to Thuy-Yung TRAN and Edward HOARE         filed 15 Dec. 2011, entitled “System for a Vehicle 1” (agent Ref         PWO1110716/JLR10-042WO1);     -   2. PCT application ______ to Thuy-Yung TRAN and Edward HOARE,         filed 15 Dec. 2011, entitled “System for a Vehicle 2” (agent Ref         PWO1110717/JLR10-042WO2);     -   3. PCT application ______ to Thuy-Yung TRAN, Edward HOARE and         Nigel CLARKE, filed 15 Dec. 2011, entitled “Vehicle Control         System” (agent Ref PWO1110718/JLR10-043WO);     -   4. PCT application ______ to Thuy-Yung TRAN, Edward HOARE and         Nigel CLARKE, filed 15 Dec. 2011, entitled “Wading Depth         Estimation” (agent Ref PWO1110719/JLR10-044WO);     -   5. PCT application ______ to Thuy-Yung TRAN, Edward HOARE and         Nigel CLARKE, filed 15 Dec. 2011, entitled “Vehicle Orientation         Device and Method” (agent Ref PWO1110721/JLR10-045WO2);     -   6. PCT application ______ to Thuy-Yung TRAN, Edward HOARE and         Nigel CLARKE, filed 15 Dec. 2011, entitled “Wading Vehicle Depth         Measurement Apparatus 2” (agent Ref PWO1110722/JLR10-046WO);     -   7. PCT application ______ to Thuy-Yung TRAN, Edward HOARE,         Anthony JONES, Simon THOMSON and Ashutosh TOMAR , filed 15         December 2011, entitled “Wading Vehicle Display 1” (agent Ref         PWO1110723/JLR10-047WO1);     -   8. PCT application to Thuy-Yung IRAN, Edward HOARE, Anthony         JONES, Simon THOMSON and Ashutosh TOMAR, filed 15 Dec. 2011,         entitled “Wading Vehicle Display 2” (agent Ref         PWO1110724/JLR10-047WO2);     -   9. PCT application to Thuy-Yung IRAN, Edward HOARE, Anthony         JONES, Simon THOMSON and Ashutosh TOMAR, filed 15 Dec. 2011,         entitled “Wading Vehicle Display 3” (agent Ref         PWO1110725/JLR10-047WO3);

The contents of the above referenced PCT applications (and corresponding UK applications, filed concurrently and having the same ownership, inventorship and Title as the above listed PCT applications) are hereby expressly incorporated by reference in their entirety into the present application. 

1. An apparatus for water level measurement for a vehicle, the apparatus comprising a capacitive or resistive water level sensor exposed in use to water at wading depth.
 2. An apparatus according to claim 1 in which the water level sensor is configured to detect the level of water over a prescribed range.
 3. An apparatus according to claim 2 in which the water level sensor is configured to detect changes in the water level continuously.
 4. (canceled)
 5. An apparatus according claim 1 in which the water level sensor comprises a pair of elongate electrodes oriented in a vertical sense with respect to the vehicle local coordinate system such that the water level may be determined by measuring the resistance and/or capacitance across the water level sensor electrodes.
 6. An apparatus according to claim 1 in which the sensor comprises an array of electrode pairs oriented in a vertical sense with respect to the vehicle local coordinate system and wherein the water level sensor is configured to detect changes in the water level in a plurality of discrete levels.
 7. An apparatus according to claim 1 in which the sensor comprises a single electrode on a first side of the sensor and a plurality of electrodes on a second side of the sensor and wherein the water level sensor is configured to detect changes in the water level in a plurality of discrete levels.
 8. An apparatus according to claim 6 wherein one of the electrodes is formed from a component of the vehicle.
 9. (canceled)
 10. An apparatus according to claim 1 in which the water level sensor is positioned below the engine air intake. 11-12. (canceled)
 13. An apparatus according to claim 1 wherein the water level sensor is activated by a wading sensor and wherein the wading sensor is an ultrasonic sensor configured to detect the presence of water upon immersion thereof.
 14. A vehicle comprising a water level measurement apparatus. comprising a capacitive or resistive water level sensor exposed in use to water at wading depth.
 15. A vehicle according to claim 14 further comprising: an angular orientation sensor; and a water level detection control system comprising a memory and a processor, in which the memory is configured to store a water level measurement from the water level sensor and a vehicle orientation from the angular orientation sensor, the memory further storing software executable by the processor to determine a water level on the vehicle at a position spaced from the water level sensor.
 16. A vehicle according to claim 14 in which the water level sensor has a position selected from the group comprising: on a front subframe, on a radiator support pack, on a bumper beam, on a wheel arch liner, on a suspension knuckle, on lower arms, on a body component, on a frame component and on an external surface of one or more components in the engine bay. 17-19. (canceled)
 20. A vehicle according to claim 16 in which multiple water level sensors are positioned across more than one component of the vehicle spaced in the longitudinal and/or transverse directions.
 21. A vehicle according to claim 16 in which multiple water level sensors are positioned across more than one component to measure water level at different heights in the vehicle body local coordinate system. 22-23. (canceled)
 24. A vehicle according to claim 20 wherein the multiple water level sensors are configured to detect a plurality of water levels, wherein the angular position of the vehicle body whilst wading can be determined, without recourse to an attitude sensor, by comparing the water level at different positions on the vehicle body.
 25. A method of detecting the wading depth of a vehicle comprising: providing on the vehicle a capacitive or resistive water level sensor; and determining wading depth according to the capacitance or resistance thereof, respectively.
 26. A method according to claim 25 comprising the step of providing a vertical array of said water level sensors, each water level sensor being independent so as to indicate a discrete wading depth.
 27. A method according to claim 26 comprising the step of interrogating selected from the group comprising: interrogating each water level sensor in the array individually; interrogating each water level sensor in the array individually in a predefined sequence; and interrogating two or more water level sensors in the array simultaneously. 28-31. (canceled)
 32. A method according to claim 25 further including determining orientation of the vehicle from an orientation sensor, and determining a water level on the vehicle at a position spaced from said water level sensor.
 33. A vehicle body component comprising an a water level measurement apparatus according to claim
 1. 34. (canceled) 